In wafer manufacturing industry, silicon ingot is required to be sliced into wafers. Conventionally, silicon ingot is bonded and fixed on a support by using an adhesive, and then the silicon ingot is sliced into wafers. Accordingly, as for the adhesive composition used for wafer manufacturing, on one hand, the bonding between the silicon ingot and/or the sliced wafer and support should be sufficiently strong so as not to cause bonding failure; on the other hand, there is a need for the adhesive to be removed from the wafer after the slicing of the silicon ingot has completed. In other words, such an adhesive composition is temporarily bonded.
U.S. Pat. No. 4,897,141A discloses a process of preparing semiconductor wafers from ingots by bonding said ingots to a cutting beam with an epoxy adhesive and slicing the ingot into wafers, said process comprising the steps of: a. mixing hollow microspheres with the resin part of an epoxy adhesive, wherein the hollow microspheres are formed from silicate glass melts, etc.; b. mixing a hardener for the epoxy adhesive with the mixture of step a.; c. coating the mixed adhesive system on said cutting beam and/or semiconductor; d. contacting the cutting beam with a silicon ingot; e. allowing the adhesive to cure; f. slicing the ingot into wafers; and g. recovering the wafers by breaking the adhesive bond between the semiconductor wafer and the cutting means.
JP9157628 discloses a temporarily bonding adhesive, which comprises one or more of rosin resin or modified rosin resin, and its preparation method is to mix the rosin resin or modified rosin resin with dibasic acid or styrene-acrylic acid copolymer, and to dissolve the resulting mixture in an aqueous alkali solution at pH 7.5-14. The adhesive is used by uniformly coating the wafer therewith, volatilizing water or other volatile components in the adhesive by baking, then heating the resulting wafer at a temperature higher than the softening point of the resin, allowing the prepared wafer to temporarily bond, and then cooling it down. The resulting adhesive is peeled with a knife, etc., after the wafer is processed.
JP7224270 describes a temporarily bonding adhesive which comprises a fatty acid ester of polyglycerine, an adduct of polyglycerine with ethylene oxide and an adduct of polyglycerine with a propylene oxide as active ingredients of the adhesive. In addition, the adhesive is difficult to dissolve in cold water, but is easy to dissolve in hot water. Consequently, after application, the adhesive is removed by using hot water.
While the above temporarily bonding adhesives for silicon ingot slicing are present in the prior art, there are still needs for a temporarily bonding adhesive combining better bonding effect and ease of demounting.